This invention relates to a water proof structure for an engine starter motor for use in a vehicle and, more particularly, to a water proof structure provided in a front bracket of the starter motor.
FIGS. 1 and 2 are a sectional side view and a front view, respectively of an engine starter motor with a conventional water proof structure. In FIGS. 1 and 2, The engine starter motor comprises a d.c. motor 1 having a yoke 2 to which a plurality of magnetic poles 3 are attached. A rear bracket 4 is secured to the rear end of the yoke 2, and a front bracket 5 is secured to the front end of the yoke 2. The rear bracket 4 and the front bracket 5 rotatably support the rotary shaft 7 of an armature 6 through rear and front bearings 8 and 9. The rear bracket 4 also supports a brush assembly 10.
Within the front bracket 5, an over-running clutch 11 axially slidably mounted on the rotary shaft 7 is disposed. The over-running clutch 11 includes a clutch inner member (not shown) on which a pinion 12 is integrally formed. In order to limit the forward movement of the pinion 12 along the rotary shaft 7, a stopper 13 is disposed on the rotary shaft 7.
The starter also comprises a solenoid switch 14 which, when actuated, magnetically attracts a plunger 15 to pull a hook 16 rearward. The hook 16 of the solenoid switch 14 is connected to one end of a shift lever 17 which is pivotaly supported by the front bracket 5 at the pivot point 17a and connected at the other end to the over-running clutch 11 for axially moving the over-running clutch 11 and the pinion 12 back and forth on the rotary shaft 7.
The front bracket 5 has formed therein an opening 5a for allowing the pinion to project therethrough and engage a ring gear (not shown) of an engine to be started when the starter is actuated. The front bracket 5 also has formed at the bottom portion of the rear edge abutting against the front edge of the yoke 2 a water draining notch 5b which defines together with the front edge of the yoke 2 a draining hole 5c.
When the solenoid switch 14 is energized, the plunger 15 pulls the hook 16 rearwadly to cause the counterclockwise rotation of the shift lever 17 about the pivot point 17a. Then, the shift lever 17 causes the over-running clutch 11 to slide forward along the rotary shaft 7 to bring the pinion 12 on the clutch inner member of the over-running clutch 11 into engagement with the engine ring gear (not shown). Simultaneously with the forward movement of the pinion 12, movable contacts (not shown) on the plunger 15 of a solenoid switch 14 engage the stationary contact (not shown), whereby an electric power source is connected to the d.c. motor 1 to rotate the motor armature 6 which, through the pinion 12, causes the engine ring gear to be driven to start it.
With the conventional water proof structure for an engine starter motor as explained above, water splashes or water drops can enter into the starter through the pinion opening 5a of the front bracket 5. The entered water or mositure is discharged from the housing through the draining hole 5c formed in the front brackcet 5. However, particularly when a large amount of water has entered into the front bracket 5, the water may enter into the yoke 2 and the rear bracket 4, causing the improper or erroneous operation of the engine starter motor.